Preface

Summary

Wireless Fidelity (Wi-Fi) networks have become mainstream over the last few years. What started out as cable replacement for static desktops in indoor networks has been extended to fully mobile broadband applications involving moving vehicles, high-speed trains, and even airplanes. Perhaps lesser known is the proliferation of unique Wi-Fi applications, from Wi-Fi mosquito nets (for controlling malaria outbreaks) to Wi-Fi electric utility and parking meters to Wi-Fi control of garden hose sprinklers. The global revenue for Wi-Fi was nearly $3 billion at the end of 2006 and will continue its upward trend in the coming years.

When Wi-Fi wireless LANs were first deployed, they give laptop and PDA users the same freedom with data that cellphones provide for voice. However, such networks need not transfer purely data traffic. It can also support packetized voice and video transmission. People today are spending huge amounts of money, even from office to office, calling by cellphones. With a Wi-Fi infrastructure, it costs them a fraction of what it will cost them using cellphones or any other equipment. Thus, voice telephony products based on 802.11 have recently emerged. A more compelling use of Wi-Fi is in overcoming the inherent limitations of wireless WANs. An increasing number of municipal governments around the world and virtually every major city in the U.S. are financing the deployment of Wi-Fi mesh networks with the overall aim of providing ubiquitous Internet access and enhanced public services.